I'm in the process of setting up my first freshwater tank. Hoping to add first fish this weekend (ie tomorrow), but I've been testing my water over the past couple of days and all the readings are fine - except gH, which is showing as low - around 0 degrees.

Is it safe to add fish? Or do I need to fix that first? The testing kit says that adding Calcium Carbonate would increase the hardness of the water. So should I do that? And if so, how? Is it something I can buy in my local aquarium supplies shop?

Did you use RO water? Did you also test kh? What was your ph? I add Barr's GH booster. It's only a few dollars a pound.

No, just regular tap water.

I tested pH, Carbonate (KH), General Hardness (GH), Nitrate (NO2), Nitrite (NO3) and Chlorine (CL2) - everything except GH looked fine.

So should I add some GH booster before I think about putting in fish?

What was the kh? Should be in the 3-4dkh range for the water to be safe. Water that is very low gh sometimes has very low kh. Why I asked. I would get some gh booster or Seachem's Equilibrium.

The gh test is one of the more difficult test to run.

Maybe I missed it, are you doing a fishless cycle? If the tank hasn't cycled yet, careful adding fish. research nitrogen cycle.

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100 Dirt + Stuff. To be Angel baby tank.
37 Planted. http://www.aquariumforum.com/f45/pla...nal-20774.html
29 Tall community tank. 5+ Years up and running.
15 Soon to be RCS tank.

Yes, it's a fishless cycle. I've been using testing strips to test the water, so don't have exact figures for any of the water tests, but everything except GH was in what the strips called "OK" levels.

I wouldn't trust strips to do anything other than to tell me I may need to take a closer look at something by performing a more accurate liquid test. In other words, I wouldn't make a decision based on results using them.

I second jrman83's opinion about the test strips being only good to get a rough idea. Get a liquid test kit to give you a much more accurate look at your tank.

Calcium carbonate is regular baking soda by the way. But I've only ever seen it used (and used it) to raise KH. I'm sure it has an effect on GH as well, but be aware that if you add it, your KH will go up. For raising GH, Tom Barr's GH booster is a very good product.

-Clay

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Clay Turville
Southern Oak Aquatics

First I would verify the gh measurement. I agree the color change is the best test to use but the api gh test is extremely hard to see the change. It could be also the gh is very high and you haven't added enough drops.

so first get verifications of the current gh value.

To increase try a little magnesium sulfate. Commonly called epsom salts.

my .02

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fw leiden since 1979, fo salt since 1979, mixed reef 55g 2002-2009. Strong emphasis on the tank taking care of itself. Balanced with plant life, no water changes, tap water, no filters in FW. Only dosing calcium, alk, mag in marine reef tanks. http://www.aquariumforum.com/f15/my-...ods-26410.html
recent tanks (till 2009) 7 years- 10g FW leiden 7 yrs, 55g mixed reef 7, 2 yrs, 20g FW leiden, 10 g fw leiden , 29g mixed reef, current tank 55g leiden